He is a good poker in lane, but so are many other champs. He isn't as much of a lane bully as Riven is and I don't see much hate around her. Do people just hate him just because most of the community does? Just buy items to take out his mushrooms and don't use any abilities that are affected by his blind. 
I main teemo BTW (^._.^) Never underestimate the power of the scouts code.
Many people hate Riven. Also, many people dislike Teemo because of his annoying poke and if he gets extremely ahead, if you step on one of his shrooms you're going to get chunked hard if you have no MR. He is also the League equivalent to Satan.
I have experience in this field. Here's the easiest way to get somebody off your back:
Fk off Teemo u pice of poo
Don't make me spam my laugh.
oh
I feel like hating on Teemo is some sort of meme that people force themselves to take seriously in order to fit in. I don't mind laning against teemo. I'd much rather lane against a Teemo than a Quinn or Vayne top.
Teemo hate is a mostly-joke that goes all the way back at least to S1 and probably into Beta. Riot even confirmed he has hidden, global taunt that just makes players want to kill him.
Cuz his shrooms hit for like 1/3 your hp if you are a squish. I actually like laning against one tho, he isn't very hard to lane against.
his shrooms are REALLY annoying, his DoTs are annoying, and his character is forcefully "too cute", which ramps up the annoyance factor for a lot of people
and depending on who you're playing, his blind (and overall kiteability) is a bitch too
The hate is purely because he conatsantly poisens everone and leaves explosive poisenous mushrooms everywhere that people walk. You just got away from a huge team fight and are the only one left alive, you move to back, then step on a shroom. . .
hes useless in team fights
